PROJECT SUMMARY/ABSTRACT The global burden of pulmonary disease is immense, with acute lung pathology affecting 1-5 million people annually and chronic obstructive pulmonary disease (COPD) the 4th leading cause of death worldwide. The best treatment for end-stage disease, lung transplantation, has a 10-year survival rate of less than 30%. Our fundamental understanding of lung cell systems biology, pathological derangements, and tissue homeostasis is truly limited. To better treat pulmonary disease, there is a need to better understand tissue biology, and a need to design new therapeutic approaches based on basic principles and regenerative engineering. This project aims to elucidate basic pathways governing microvascular regulation and homeostasis in the alveolus, and then apply those mechanisms for regenerative engineering. The proposal is divided into three specific aims. In the first aim, single-cell RNA sequencing (scRNAseq) of distal lung will be used to elucidate potential microvascular-specific growth factor signaling in the developing and mature alveolus. In the second aim, a putative list of signaling mechanisms will be further refined based on native tissue protein expression and co- localization with microvasculature. Finally, in the third aim, a limited set of identified growth factors will be delivered over time to an in vitro organotypic model to assess their effect on microvascular development and function. The project is motivated by the overarching hypothesis that understanding growth factoring signaling at the tissue level will not only aid in the understanding of pulmonary development and pathology, but will strongly inform how to ?reverse-engineer? pulmonary vascular tissues for regenerative medicine. !